GB966836A - Fluid pressure operated valves - Google Patents

Abstract

966,836. Valves. CHATLEFF CONTROLS Inc. May 3, 1963, No. 17576/63. Heading F2V. A three-way valve particularly for reversing the flow in refrigerators for defrosting, comprises a housing 1 with two aligned end outlet ports 4 and an inlet port 2 between them, valve seats 5 round the outlet ports, a pair of cylinders 7, 8 mounted in the housing between the outlet ports to allow fluid flow from the inlet to the outlets between the housing and the cylinders, the outer ends of the cylinders being open and spaced from the seats 5, each cylinder having in its inner end a central outlet opening 9 encircled inside the cylinder by a valve seat 10, a valve piston 16 slidable in each cylinder and adopted to close the adjacent outlet port 4 and outlet opening 9 alternately, the outer end of each piston 16 projecting laterally beyond the valve seat 5, a pair of conduits 14 sealed in the wall of housing 1 and each having an inner end communicating with the corresponding outlet opening 9, the inner ends of the cylinders having aligned passages 36, 36 and 37, 37 therethrough radially outwardly beside the outlet openings 9, and parallel push-rods 38 disposed between the pistons 16 with their ends in these passages for movement lengthwise therein, the rods being just long enough to push a piston outward from its cylinder seat to a position near the adjacent outlet port when the other piston moves inward, a rod end portion at each cylinder being reduced in diameter as shown for a distance sufficient to expose the surrounding passage to the fluid pressure in the housing 1 only when the piston in that cylinder is near the valve seat 10 therein, and the outer ends of the conduits 14 being adapted to be connected alternately with a region of lower pressure than the pressure in housing 1 to cause the pistons alternately to move inwardly to engage the cylinder seats. As shown for a refrigeration system in which defrosting can be accomplished by reversal of the flow direction of the refrigerant, the conduits 14 are connected through a solenoid operated pilot valve 22 with a low pressure line 40 connected to the compressor inlet. The top outlet 4 is connected with a line 47 leading to the evaporator and bottom outlet 4 with a line 48 from the condenser. Inlet 2 is connected to the compressor outlet. A leaky double piston reversing valve 53, 54, 55 is automatically reversed by operation of the valve pistons 16, so as to effect reversal of the flow direction of the refrigerant.